Atomized metal



Patented Feb, 8, 1949 A'EUMIZED METAL Gordon J. Le Brasse, Ann Arbor, and Harold E.

Francis, Detroit, Mich, assignors to Federal- Mognl Corporation, Detroit, Micln, a corporation of Michigan No Drawing. Application February 6, 1946, Serial No. 645.9%

This invention relates to a new article of manufacture comprising atomized metal and particularly metal which consists of an alloy containing as essential elements material amounts of both copper and lead, the principal object being the provision of an atomized alloy of the character described having new and novel characteristics greatly enhancing its commercial value.

Objects of the invention include the provision of an atomized metal alloy, containing as principal elements thereof, copper and lead, having not more than of 1% of oxygen included therein, and the provision of an atomized alloy of the character described in which the various particles of the atomized alloy are spheroidal in character, of a color equivalent to that of a freshly machined surface of the same metal when cast, and have a bright shiny lustre.

While particles of atomized alloys of which copper and lead are material elements and occur in material percentages are useful for many different purposes, perhaps the principal use of the same at the present time is that of a bearing facing, particularly for rotating shafts such as the crank shafts of internal combustion engines. A conventional method of using such atomized alloys in the fabrication of a bearing is to apply a coating of the atomized metal or powder to a face of a ferrous metal strip. such as steel, and

pass such coated strip through a furnace at such temperature and for such a length of time as to cause the atomized metal to be sintered, thereby causing the various particles to adhere to one another and to the steel backing strip. After the sintering operation, the coating of sintered metal is conventionally compressed against the steel strip, the coated strip thus formed out into suitable lengths and then bent into either half bearings or full cylindrical bearings, and then subjected to suitable machining or other operations to bring them to the desired final internal, external and axial dimensions. Y The alloys thus employed may be what are commonly termed as either a copper-lead alloy in which the elements of copper and lead are the main elements of the alloy, or a lead bronze in which copper, lead and tin are the principal al- 2 @laims. (El. -463) alloy into fine particles.

loying elements. Various other alloying or other vention is as follows:

' Per cent Lead 10 to 50 Nickel ii to 2 Tin 9 to 2 Phosphorus lite 0.10 Copper substantially the balance A satisfactory composition for a bronze in accordance with the present invention may be as follows:

Per cent Lead 5 to 30 Tin 2 to 12 Zinc Oto 6 Nickel 0 to 2 Phosphorus ilto 0.5 Copper substantially the balance Alloys in which copper and lead are the major or are among the major elements and are within the scope of the present invention are usually produced in a conventional manner, and are then atomized by allowing fine streams of the molten alloy to be discharged into a blast or a spray of water in air which breaks up the stream of molten The particles thus formed are gathered and screened so as to eliminate those of a size considered too large for desirable practice, those of excess size being returned to the melting pot and again subjected to the atomizing operation. For use as a bearing material in the manner above described, particles of a size capable of passing through a mesh screen are usable, although ordinarily it is desirable that they be of a still smaller size, as for instance, that capable of passing through a or a mesh screen.

The conventional method of producing atomized alloys of the character stated results in the formation of a very apparent outside coating on the particles thus formed. In the copper-lead alloy, such coatings will be ordinarily found to becomprised substantially entirely of lead oxides, and in the case of the particles of lead bronzes the greater percentage of the coatings will be found to be lead oxides, but there will usually be found tin oxide in greater and lesser amounts ddition thereto. There are live different as of lead, but in view of the temperatures .ved it is presumed likely that one or all of ollowing three lead oxides are present in such ng: Plot), PbsOr and PbzOs.

.lBil. such alloys are atomized in the conveni as above described, the oxygen conoi' the oxides thus formed during the atomin will be found to be in excess of 1% of the weight oi the alloy, usually in the neighao'd or" 1.2%. The average oxygen content 1e three lead oxides above listed in 8.6%. is average-figure is used as a basis for caling the amount of oxide present in a mass 1e atomized alloy, then an atomized mass zch an alloy having 1% of oxygen would i that there would be about 11.6% lead oxide nt. With average oxygen content of then there would be about 13.92% of lead present in an atomized mass of the alloys Le under consideration when convenlly atomized. e amount of oxides present in atomized alaf the character under consideration when ized in the conventional manner is so great the resulting atomized alloy or powder is dark reddish brown color in the caseof a er lead alloy, and of a more grayish color 2 case ieadbronze, and both substanof lustre. Although the particles 'eacl alloy are spheroidal incharaces oi the lead bronze will be r strings. L61: atomized metal alloys of the character cor'isideral'iion and produced in 'a convenl manner are employed to form a bearing ce on steel strip in the manner first derd, it is necessary, in passing the coated through a sintering furnace, to employ a ing atmosphere and to insure that the strip Ins in the furnace under the influence of seducing atmosphere for such a length of and such temperature, that a material rtion or" the oxide coating on the particles lueed, as otherwise it has been found that satisfactory bond between the particles and ;eel strip, and between the particles themwill result. [as been found that unless the oxide coating lch particles is reduced in the sintering cc to a point at which the total oxygen at of the mass of atomized particles does mbstantially exceed 0.6% of the weight of articles, the resulting alloy will be too brittle eadily cracked and broken for satisfactory l both the forming operations and in servnd, additionally, because of its weak bond the steel backing, it has a tendency to pull from the latter. v v it will be appreciated that the length of required to pass a steel strip coated with a of particles of atomized'alloy of the charunder consideration, and which particles lated with a conventional amount of oxide, gh a sintering furnace under the influence educing atmosphere in order to reduce the coating or" the particles to an extent sufto render the bond between the particles :elves and between the particles and the backing membersatisfactory, is greatly in of the time which would be required were :duction of the oxides not necessary. As a r of fact, tests have shown that in order tain an equivalent bond, at least twice as time is required for the passage of the coated strip through the sintering furnace where the particles have a conventional amount of oxide coating as in a case where the oxygen content of the coating before entering the sintering furnace is not in excess of'that below which the desired bond is effected. vWhere the oxygen content is not over 0.2% of the weight of a mass of such particles, the sintering operation may be accomplished in one-third or less time than where the particles of themass have a conventional amount of oxide coating on them. Additionally, the amount of non-oxidizing or reducing gas used in the sintering oven is materially reduced inasmuch as less steam is formed due to the fact that very little, if any, oxide is reduced in such furnace. With the large amounts of oxide present in atomized metal produced conventionally, and such oxide is reduced in the sintering furnace, the amount of steam formed in the reducing of the oxides actually drives large amounts of the reducing gas out of the furnace.

The present invention comprises atomized particles of the alloys herein under consideration in the form of a generally loose mass or powder and the particles of which have an oxide coating, the oxygen content of which does not exceed 0.5% of the weight of such particles. This does not necessarily mean that the oxide inclusion of each" and every particle of a mass of such particles is not greater than 0.5% of the mass of such particles but, rather, that for a. given mass of such particles the oxide coating thereon does not exceed 0.5% of the mass of the particles collectively.

The particles of atomized metal of the alloys in question, in accordance with'the present invention, are definitely visually differentiated from equivalent particles formed in the conventional manner. In the case of the present invention 40 the particles are of' a-color substantially equivalent to that of a freshly machined surface of the same metal when cast. In the case of the copper lead alloy of the analysis given above, the color is a bright copper color,- and in the case of a lead bronze of the analysis given above, the color is, of course, lighter and more bronzy due to the inclusion of the tin and/or zinc. In both cases the particles have a shiny metal lustre. Additionally, the particles of both the copper lead alloy and the bronze are spheroidal in shape. Because of their low oxygen content loose atomized particles of the alloys under consideration may be applied as a coating to a steel strip and passed through a sintering furnace without regard to any necessity of reducing the oxygen content of the mass. Experiments have definitely determined that strips of steel coated with atomized metal of the present invention may be passed through a sintering furnace at twice or more the speed required to obtain a satisfactory result when employing conventionally formed atomized alloys of the character under consideration, and the resulting products are at least equal, if not ,in all cases superior, to those resulting from the use of conventionally formed atomized particles.

In the broader aspects of the invention, the means by which atomized particles of the alloys under consideration are formed without producing an oxide coating resulting in an oxygen content in a mass of such particles no greater than 0.5% of the weight of such mass, is immaterial. Such particles may, however, be readily produced by the method and apparatus disclosed in our copending applications for Letters Patent in the United States for improvements in Method of atomizing metal, and Apparatus for atomizing metal, respectively, filed on even date herewith. and serially numbered 645,947 and 645,946 respectively. Particles of the alloys under consideration may be easily produced in the manner disclosed in said copending applications with a resulting oxygen content normally not exceeding about 0.2% of the weight of a mass of atomized particles produced thereby, and have been produced in the laboratory with such oxygen content as low as 0.06% and as low as 0.08% in production. Such particles are, obviously, ideally suitable for the manufacture of hearings in accordance with the method herein described and, equally obviously, not only result in a bearing which may be more readily and quickly formed from the coated steel strips, but one which is of superior characteristics in service. Equivalent advantages are apparent in the manufacture and quality of other objects produced wholly or in part from such particles of metal.

Having thus described our invention, what we claim by Letters Patent is:

1. A new article of manufacture comprising an atomized copper alloy] in the form of a loose mass of particles of no greater size than that capable of passing through a 100 mesh screen, said alloy consisting of to 50% lead, up to 2% nickel, up to 12% tin, up to 6% zine, up to 0.5% phosphorus, and the balance copper, characterized by the fact no greater than 0.2%.

GORDON J. LE BRASSE. HAROLD E. FRANCIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 646,119 Ciamer et al. Mar. 27, 1900 1,541,609 Adams June 9, 1925 1,635,653 Williams July 12, 1927 1,761,506 Williams June 3, 1930 2,384,892 Comstock Sept. 18, 1945 FOREIGN PATENTS Number Country Date 553,672 Great Britain June 1, 1943 

